Exploration of the use of the combined power of Computer Assisted Tomography (CAT) scanning and Positron Emission Tomography (PET) scanning to study brain cell metabolism in diseases associated with aging is the purpose of his project. The initial goal is to provide a computerized image analysis procedure to delineate brain substructures represented in spatially, sequenced CAT scan images and to determine metabolic activity in these substructures from corresponding sequenced PET scan images.